1. Purpose and scope 

Every patient receiving a fresh blood product needs a valid pretransfusion compatibility testing/blood group and antibody screen performed at the Royal Children's Hospital  (RCH) prior to blood transfusion.

The purpose of this document is to provide guidance on pre-transfusion testing for clinicians prescribing blood products for children at The Royal Children’s Hospital (RCH).

2. Definitions 

3. Guideline 

3.1 Pre-transfusion compatibility testing 

It is essential to correctly identify the patient during the collection of a pre-transfusion sample to avoid taking the wrong blood sample from the wrong patient. Errors associated with patient identification pose a significant risk to patients, and risk of an incompatible blood transfusion by providing the “wrong blood to the wrong patient”.

All specimen collection and labelling must be done in accordance with the RCH Specimen collection procedure and Blood transfusion - fresh blood products procedure. 

3.2 Blood group and antibody screen 

A Blood group and antibody screen (BGAB) is necessary prior to any routine or non-emergency transfusion. It should be requested if a patient is planned for surgery where blood loss is expected or they require a planned red cell transfusion. It includes the following:

- Determines the ABO group and RhD type of the recipient

- Screens for clinically significant red cell antibodies in the patient’s plasma

- Determines the specificity of any red cell antibodies (if positive antibody screen)

The patient's current blood group must agree with any previous record of the patient’s blood group. If there is any discrepancy with a historical blood group, investigation and repeat testing will be required to confirm the patient’s blood group. 

3.3 Crossmatch 

The BGAB sample is used to crossmatch appropriate donor red cells and ensure compatibility between the patient’s plasma and donor red cells. This may be performed by electronic methods or serologically.

When a patient does not have any current or historical antibodies, compatible units are selected and issued electronically.

Any patient with a red cell antibody detected requires further laboratory work to identify the specificity of the antibody, to type the patient and donor units and perform a full serological crossmatch to ensure the blood is compatible with the patient. For patients with multiple antibodies this investigation can take several hours to complete. Patients with a history of previous clinically significant antibodies will require a serological crossmatch. 

3.4 72-hour rule 

The 72-hour rule refers to the period of sample validity of the pretransfusion sample, whereby it may be used to provide crossmatched blood.  This is an internationally accepted safeguard is used to prevent a transfusion reaction in patients who form antibodies to foreign red cell antigens in response to pregnancy or transfusion.

At RCH the BGAB for transfusion expires 72 hours after collection.  A fresh BGAB sample will be required once 72 hours have elapsed if further red cell transfusions are required.

The time and date of collection of the cross-match specimen is indicated in the Electronic Medical Record (EMR). If a unit of red cells is ordered in EMR without a current BGAB, a prompt will appear with the option to order the BGAB at the time of ordering the red cells.

The only exceptions to the 72-hour rule are for some neonates and infants during the first four months of postnatal life (neonatal extended expiry) or those patients who have extended expiry crossmatching completed prior to having planned surgery (extended expiry) meeting certain criteria. 

3.5 Neonatal extended expiry 

The neonatal extended expiry (ASBT protocol) prevents repeated BGAB testing prior to transfusion for infants meeting certain criteria during the first 4 months of life. This protocol recognises that the development of alloantibodies to red cell antigens is very uncommon in the first 4 months of life. The protocol reduces the requirement for repeated pre-transfusion blood sampling.

The Blood bank will assess a neonate/infant’s eligibility according to established criteria:

• Age less than 4 months age
• Pre-transfusion ABO and RhD group have been performed
• Are DAT negative
• Have no red cell antibodies (e.g. clinically significant maternal antibodies).
• A continuous hospital admission

If accepted, the laboratory will issue a report indicating that a further sample will not be required for further BGAB samples until the baby is 4 months of age and will specify this date. Blood products may be issued by electronic crossmatch.

When requesting the neonatal extended expiry, please indicate any previous transfusion history (e.g., intrauterine transfusions, exchange transfusions or top up transfusions) and the hospital of birth or transfer. 

3.6 Extended expiry 

Extended expiry allows patients undergoing planned spinal, craniofacial or cardiac surgery to have a BGAB performed prior to surgery and remain valid for a maximum of 30 days prior to the surgery date. The anticipated date of surgery and type of surgery can be outlined in the medical order for the BGAB.

For the extended expiry BGAB to remain valid, the following conditions must be met prior to sampling and maintained throughout the 30-day period.

• No transfusions in the preceding three months
• No pregnancy in the past three months .
• The blood bank must receive a signed declaration from the parent/guardian/patient in order to validate the sample.
• No red cell antibodies have been detected
• The DAT must be negative

If any of these conditions change in the lead up to surgery, the parents/guardians/patient will have instructions to contact the blood bank to inform them of these changes. Another blood test will be required to confirm the BGAB prior to surgery. 

3.7 Pre-transfusion sample requirements  

3.8 Key aligned documents/resources 

• Australian and New Zealand Society of Blood Transfusion Guidelines guidelines: Guidelines for transfusion and immunohaematology laboratory practice (2020)   

• Safer care Victoria: Transfusion for neonates